This invention relates to a system of noise attenuation around an air induction assembly.
Manufacturers have employed active and passive methods to reduce engine noise within a passenger compartment of a vehicle. Such noise frequently emanates from the engine, travels through the air induction system and emanates out of the mouth of the air intake into the passenger compartment. Efforts have been made to reduce the amount of engine noise traveling through the air induction system. These efforts include the use of both passive devices, such as expansion chambers and Helmholtz resonators, and active devices involving anti-noise generators.
Active systems use a speaker to create a canceling sound that attenuates engine noise. The sound created is out of phase with the engine noise and combines with this noise to result in its reduction. Generally, this sound is generated in proximity to the mouth of the air induction system. In one such system, a control unit, such as a digital signal processor, obtains data from the vehicle engine, creates a predictive model of engine noise, and then generates the appropriate canceling signal based on the results of this model. This signal is then transmitted to the speaker, which transforms this signal into a canceling sound. Because the control unit may not perfectly model engine noise, an error microphone is placed in proximity to the mouth of the air induction system to determine if engine noise need be further attenuated.
The microphone for such a system is typically mounted to the speaker housing and located at the mouth of the air intake. This location, however, subjects this sensitive device to the hostile environment around the air intake mouth, exposing the microphone to road conditions, debris, and foul weather. As a consequence, the microphone may be damaged during vehicle operation resulting in the malfunctioning of the noise attenuation system.
In addition, the noise attenuation system is frequently made of a number of separate components, which require assembly on the production line of the vehicle. These components include the microphone, the speaker and speaker volume, and air filter. The separate assembly of these components into the air induction system accordingly results in reduced productivity.
A need therefore exists to provide a more robust and simplified noise attenuation device for an air induction system.